660656551 has 4 divisors (see below), whose sum is σ = 660732400. Its totient is φ = 660580704.

The previous prime is 660656519. The next prime is 660656561. The reversal of 660656551 is 155656066.

660656551 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 155656066 = 2 ⋅77828033.

It is a cyclic number.

It is not a de Polignac number, because 660656551 - 2⁵ = 660656519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660656561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22866 + ... + 42943.

It is an arithmetic number, because the mean of its divisors is an integer number (165183100).

Almost surely, 2^660656551 is an apocalyptic number.

660656551 is a deficient number, since it is larger than the sum of its proper divisors (75849).

660656551 is a wasteful number, since it uses less digits than its factorization.

660656551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75848.

The product of its (nonzero) digits is 162000, while the sum is 40.

The square root of 660656551 is about 25703.2400875843. The cubic root of 660656551 is about 870.9473764113.

The spelling of 660656551 in words is "six hundred sixty million, six hundred fifty-six thousand, five hundred fifty-one".